What caused it?
What sparked the explosion is still unknown.
But Lebanon's Interior Minister said the blast was a store of about 2,750 tonnes of seized ammonium nitrate blowing up.
It had been in storage since 2014, but the details about why it was seized and where it came from are unclear.
A massive stockpile of ammonium nitrate blew up in the Beirut explosion. Here's what else we know
Lebanon's Prime Minister says about 2,750 tonnes of the highly explosive material was stored in a "dangerous warehouse".

The texas 2013 fertiliser explosion was 270 tonnes.
Tianjin 2015 800 tonnes.